[NRRPLT-3902][NRRPLT-4058][NRRPLT-4840] Vizcluster support, stability, and test patch.

This patch addresses 3 broad issues:

[NRRPLT-3902]
- provides the ability to run simulations on vizcluster nodes
- parameterize absolute paths with appropriate NRP_ environment variable that can be
  properly expanded on the target host
- provides generic interfaces that can be extended for different hosts

[NRRPLT-4058]
- refactors the init/run mechanisms to more closely mirror the single process version
- this enables reporting of launch failures all the way through CLE initialization (which
  includes things like Gazebo launch failures, resource allocation failures, Exceptions)
- checks the runtime return code to determine if the mpirun command was abnormally
  terminated and properly reports the error
- propagates all errors appropriately back to the main pipeline

[NRRPLT-4840]
- increases test coverage of the new components back up to ~90%
- the reamining coverage is primarily for workaround/temporary code that is difficult to
  unit test without running the platform and will be removed in future commits

Change-Id: Ib33a1d35b26aeee6da10c95f30bb9be9243479dc